1. Field of the Invention
The instant disclosure relates to a conductive structure, and a solid capacitor and a method of making the same, and more particularly, to a conductive structure having an embedded electrode, and a solid capacitor having an embedded electrode and a method of making the same.
2. Description of Related Art
An already known solid electrolytic capacitor has a configuration constituted by an anode, a dielectric layer, an electrolyte layer and a cathode, and is generally obtained by forming, on a metal having a valve action (valve-action metal) and constituting an anode, an oxide film as a dielectric layer (hereinafter called a dielectric layer), then forming thereon a solid electrolyte layer as a semiconductor layer and further forming a cathode member of, for example, graphite. The valve-action metal is a metal capable of forming an oxide film of a controllable thickness by anodizing, and can be Nb, Al, Ta, Ti, Hf, Zr etc., among which Al and Ta are principally utilized for the practical purposes. Of these, Al is employed as the anode in a form of an etched foil, while Ta is employed as the anode in a form of a porous material formed by powder sintering. An electrolytic capacitor of the porous sintered type can be with a particularly small size and a large capacity relative to other solid electrolyte capacitors, and is in strong demand as a component capable of enabling reduction in size of a mobile telephone a portable information terminal equipment etc.
For example, a known solid electrolytic capacitor utilizing Ta is obtained by forming a dielectric layer on a surface of an anode member formed by sintering a powder mixture in which a lead wire is embedded, and then forming, on the aforementioned dielectric layer, a conductive polymer layer, containing for example carbon powder, as a solid electrolyte layer. On the electrolyte layer formed as a semiconductor layer, a graphite paste layer and an Ag paste layer are formed which function as a cathode. Then lead frames are connected respectively to the lead wire of the anode member and the Ag paste layer, and the entire structure is resin molded so as to expose these lead frames. In such a known solid electrolytic capacitor, the electrolyte layer includes many cavities, into which conductive particles constituting the cathode member formed on the electrolyte layer penetrate. Such a phenomenon, when present extensively, provides an advantage of lowering an equivalent serial resistance (ESR) of the solid electrolytic capacitor itself, and also provides an advantageous effect of securing a capacitance even at a high frequency. However, the ESR of the known solid electrolytic capacitor is increased due to the usage of the lead frames.